In 1873 an electrical
engineer named Willoughby Smith discovered that the resistance of the element
selenium, when in metal form, would vary dramatically whether or not it was
being exposed to light. This meant that Selenium was a photoconductor, and its
photoconductivity would eventually provide a method for converting images into
electric signals -- which would allow for the greatest invention of all time:
the television. A few years later, other scientists discovered selenium
could be used to create electricity from sunlight. When photons hit a
photoconductive metal, the electromagnetic radiation is absorbed, and a couple
of electrons are released. Enough electrons, and you've got yourself an
electrical current.
For the next century,
scientists studied this photoelectric effect and discovered a number of other
elements displayed photoelectric properties, and suddenly they were being used
everywhere for everything: from TVs, telecommunications, fiber optics, infrared
cameras, plus the solar panel and photovoltaic cell, which was invented in the
1950s and became popular when the space program started using them to power satellites.
By the 1970s, the cells were modernized to the point where they could be used
in commercial and residential power. At this point, consumers were still mainly
using them for calculators, and watches.
Just like a battery,
a photovoltaic cell has a positive and a negative end, which guide the
electrons into the circuit. Each cell uses a pair of silicon wavers--one coated
with phosphorous (negative) and one with boron (positive). Innovations, new
materials, and government-subsidies have driven down prices considerably. A new
study from the University of Queen Mary in London showed that they were able to
create cheap solar panels out of crushed up old shrimp shells, which could
decrease prices down even more! Do you have any solar power cells anywhere
on your house? Any other questions, please feel free to ask 'em down below.
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